Earlier this year I was asked by a NEFRA member if I would write an article to increase awareness on the dangers of salt poisoning in dogs for the Wagging Tails newsletter. At the time there tonnes of salt being spread over our roads and concern was expressed that this was potentially dangerous to dogs.
My initial response was that I had never come across a case and so I decided to read up on the subject before writing about it. In doing so I found was that it is rare but it can occur.
Sources of salt
Salt (sodium chloride) may be accessed by dogs in various different ways, including table or cooking salt, dishwasher salt, halite (rock salt) or in seawater. Ironically if their dog has swallowed another poison some owners will use a salt solution as an emetic in an attempt to make their dogs sick in order to remove a toxin.
Salt may also be found in bottle sterilising fluids, water softeners, some bath products (e.g. bath salts) and many foods (e.g. stock cubes, gravy products). It is also a component in homemade dough used for modelling.
Effects of excess salt
The body’s normal response to ingesting excess salt is simply to increase thirst to prevent any imbalance occuring in the cells. As long as fresh water is readily available the upset caused will be self limiting.
Salt has a water drawing action from the body cells. If water is not available this may lead to cellular dehydration and vascular overload. In the central nervous system this causes vascular stasis, thrombosis, brain shrinkage and shearing of the intracerebral vessels, with subsequent haemorrhage.
Signs of toxicity are expected after ingestion of 2-3g of sodium/kg bodyweight and ingestion of 4g/kg is considered lethal. An average flat-coat is 30kg so signs may be seen after ingestion of 152g of salt, that is over 5 oz of salt! This may explain why this is very rarely seen.
The first thing that sould be noticed is an increased thirst. Vomiting may be seen within a few minutes, and diarrhoea may also be seen, resulting in inevitable dehydration if fluid levels are not maintained..
Neurological signs can develop within an hour (in severe cases) or several hours later. These signs include depression, lethargy, muscular rigidity, tremor, ataxia, weakness.
The blood pressure may rise and the dehydration may lead to an increased heart rate and respiratory rate..
In severe cases neurological signs progress to seizures, coma and death.
Other signs include renal impairment or failure.
To treat salt poisoning you should seek veterinary advice.
In severe cases the vet will empty the stomach, monitor the bloods to assess electrolytes, renal function. It is important that severe cases are managed carefully, because giving too much intravenous fluid too quickly risks overhydration which the dog’s body may find it difficult to tolerate leading to a life-threatening cerebral oedema.
Mild cases may be managed simply by allowing the dog small amounts of fresh water at frequent intervals.
The prognosis is favourable in mild cases but guarded in dogs with neurological effects.
Chris Hewison BVetMed MRCVS